Question: Simplify the following expression: $z = \dfrac{-4}{r + 12} - \dfrac{-7r + 3}{r + 12}$
Solution: Since the expressions have the same denominator we simply subtract the numerators: $z = \dfrac{-4 - (-7r + 3)}{r + 12}$ Distribute the negative sign: $z = \dfrac{-4 + 7r - 3}{r + 12}$ Combine like terms: $z = \dfrac{7r - 7}{r + 12}$